Same boat as OP. 2m lifetime BIS miles but find myself flying cheaper airlines when I pay and more reliable ones when company pays.
They screw you over and say too bad. They have slashed customer service to the bone.
And they don’t care. My last 4 flights have had cancellations due to crew shortages and I got no compensation. (Including today).
Flying TATL in a month. Delta $400-600 more than the competition. Can upgrade on other airlines and have a better experience.
They won’t care, but I do.